ACT5880
Rev 2, 03-Sep-13
could start normal operation and possibly changes
the I/O output, the ACT5880 preconditions and then
charges battery with only 90mA current limit, as
specified in the "Battery Charging", until the battery
is charged to high enough voltage for device
system to start.
with VGTH greater than 2V and to be effectively
conductive when VGTH is 5V. The QOTG is used to
isolate the capacitance on 5V rail during the VBUS
pulsing required by the SRP, and also provides a
controlled path for using the external 5V from VBUS
to replace the internal 5V rail.
If USB attaching is identified in a battery normal
system, the device system should start and try to
connect the host within 100ms, as required by the
USB protocol. Within this 100ms, 100mA drawn
from the port is allowed, what is greater than the
90mA the ACT5880 takes. After the connection ,
the device system takes control of charging, either
charging as a standard load to USB port or pouring
larger current as allowed, or turning into USB
SUSPEND without charging.
Figure 22:
The Sample Circuit for Using External 5V rail.
VCC
5Vrail
RIDUP
QOTG
3V I/O
VBUS
VBUS
D-
D+
ID
Device
System
Fast Charge Current Adaptive
CHGIN
The over load to the USB port or a weak adaptor
could be identified by the loss of reading CHGIN
valid while the ACIN keeps reading valid. If the over
load happens, the device system could program the
ACT5880 to a less fast charge current volume to
make the power source normal while still getting as
much as possible power.
ACT5880
Figure 23:
The Sample Circuit of Dual-inputs and External
5V.
Dual inputs and USB-OTG Paths
VCC
5V rail
In applications that 2 power input receptacles
wanted, 2 low forward voltage diodes and a 240kꢀ
resistor RDAD are used in addition to circuit in Figure
20, as showed in Figure 21. When no suitable input
attaches to the Adaptor In, the circuit works
similarly to the circuit in the Figure 20. When
suitable input attaches to the Adaptor In, both ACIN
and CHGIN are read valid, regardless what
attaches to the USB receptacle.
R
IDUP
QOTG
3VI/O
VBUS
D-
D+
VBUS
DDN
Device
DDP USB I/F
ID
RISO
RDUP
3VI/O
3VI/O
ACIN
Figure 21:
RDDW
ACT5880
The Sample Circuit for Dual-inputs Charging.
RDAD
VBUS
VBUS
DDN
DDP
D-
D+
Device
USB I/F
Adaptor In
CHGIN
Foreign
Adaptor
or USB
RISO
RDUP
USB connectors
ACIN
Figure 23 is a sample of providing high current 5V
from an adaptor to the VBUS and for replacing the
internal 5V rail. All the 3 PFETs should be good for
control with 3V I/O, level shifters are desired
otherwise.
RDDW
RDAD
Adaptor In
CHGIN
ACT5880
Figure 22 is the typical circuit connecting a 5V
internal rail to the VBUS for providing power for
OTG application. In this circuit the QOTG has to be
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